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DROP + SENNHEISER PC38X Review (Headphone)

I would love to see this headphone measured at 60 dBSPL and see if the relative distortion keeps going down. According to this Source: Coding High Quality Digital Audio, J. ROBERT STUART that someone used on this site says that we are most sensitive to distortion at 60 dBSPL and this graph also suggests that the distortion in this headphone at the measured levels should be inaudible. Is my assessment of the distortion correct or is my source inaccurate? also Hi I'm have been lurking for a long time on this site an finally got myself to ask a question and not type a short sentence and failing to ask my question coherently.
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What is a Window's game that I can play in demo mode or something to experience such effect?
Competitive esports games like CSGO and Valorant are free to play. You can try to hop into some casual games and try to locate footsteps in there. Ever since I've been using my EQ'd Sony ZX110, I've been accused of using wallhacks in CSGO a lot, they are so detailed and able to provide pinpoint positional cues.
 
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I have to admit, I am a little confused how a headphone, well anything with this much distortion can warrant a golfing panther, and consider the poor bass response to boot. Unless I am missing something it is more than just sub bass that is lacking, some of the low bass is also lacking and the bass that is there is fairly distorted. Still, for the price I can understand the positive response, but I think we should have one symbol for overall, price not being considered, simply quality sound reproduction champs (golfing panther) and another symbol for a high performance relative to price piece of kit.
 
I would love to see this headphone measured at 60 dBSPL and see if the relative distortion keeps going down. According to this Source: Coding High Quality Digital Audio, J. ROBERT STUART that someone used on this site says that we are most sensitive to distortion at 60 dBSPL and this graph also suggests that the distortion in this headphone at the measured levels should be inaudible. Is my assessment of the distortion correct or is my source inaccurate? also Hi I'm have been lurking for a long time on this site an finally got myself to ask a question and not type a short sentence and failing to ask my question coherently.
View attachment 137154

Seems like a biolinguistic adaptation
 
This is a review and detailed measurements of the DROP + SENNHEISER PC38X gaming headphone, i.e. has microphone included. It is on kind loan from a member and costs US $159 (normally $169).

The PC38X is made entirely out of plastic but somehow feels better than "cheap" with tightly fitting parts that have a touch of class:

View attachment 137125

Two sets of cups are provided, one is the knit-mesh which is what I tested and the other, velour. This is a very light headphone at just 250 grams:

View attachment 137127

Cup inside dimensions are 69, 28, 31 mm (height, width and depth). The narrow width slightly pinches my ears but overall comfort is good. I almost forget I am wearing them.

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements even if performed with the same fixtures as mine, differ in end results. Protocols vary such as headband pressure and averaging (which I don't do). As you will see, I confirm the approximate accuracy of the measurements using Equalization and listening tests. Ultimately headphone measurements are less exact than speakers mostly in bass and above a few kilohertz so keep that in mind as you read these tests. If you think you have an exact idea of a headphone performance, you are likely wrong!

Fitting these headphones on the fixture seems to be challenging at first but on first try, I achieved excellent results with channel and frequency match so I ran with them.

Sennheiser PC38X Measurements
As usual we start with our frequency response:

View attachment 137129

Wow, what a pleasant surprise! The response essentially hugs the preferred target from 100 Hz and up. The main thing it leaves on the table is sub-bass response. Seems like someone has been paying attention to proper research into headphones and what makes them good sounding. Interesting that such a performance comes in the bargain headphone but not higher in the tier.

Relative response then shows small variations:

View attachment 137134

As usual ignore the massive dips as they are cause by multiple paths to the measurement microphone due to natural reflections. The peaks match the target which is the main thing.

All is not milk and honey though as distortion is fairly high:

View attachment 137132

Notice that peaking at 675 Hz in distortion. It coincides the same in frequency response which you can see a bit better here:

View attachment 137133

So clearly something has gone awry there. Bass distortion is unfortunate as we need to boost that area to get our sub-bass.

Group delay is not revealing of much:

View attachment 137135

Sensitivity is better than average:
View attachment 137136

Combined with relatively low impedance, you should be able to drive it with many sources:

View attachment 137137

I am listening to it with RME ADI-2 DAC and have the volume at -25 dB.

Sennheiser PC38X Listening Tests and Equalization
Out of the box the PC38X immediately impresses with correct tonality in my standardized list of reference tracks. Spatial effects though were non-existent resulting in rather uninteresting experience. Sub-bass was also absent, adding to that sensation. So I brought out the EQ and step by step, made some corrections:

View attachment 137138

The two filters on the right were there to fill the small dips in frequency response. Tonality they made the headphone a bit brighter but boy did they bring out spatial qualities. We went from C- to B+ here. I then added the sub-bass boost to balance the tonality. That was challenging as I was easily greeted with all kinds of distortion as I turned up the volume on sub-bass heavy tracks. So I played with them and at the end settled for lower levels than what I started. As is however, you need to keep the volumes to moderately loud. Anything above that and you are better off without the boost as distortion gets annoying.

Speaking of distortion, there are clearly some bad ones there. On one track I was hearing this resonance that I had not heard before. On a hunch, I went after that 675 Hz distortion peak and put in a mild notch filter. The bet was that the frequency response error was less audible than distortion. While this is a subjective assessment, I think it worked! I could not detect any penalty and I thought overall clarity improved.

I was still not super happy with the sound so went after the mild but wide peaking centered around 1400 Hz. That did it! Now we had open sound with impressive bass, and spatial qualities. I could not put down the headphone at this point and listened for the remainder of the evening. Even this morning post photography, I put them back on and am listening as I type this.

If you want a test track that shows off a headphone with great response, here it is: the Hans Zimmer's Games album and track, Wonder Woman 1984


Even without EQ the PC38X sounds good. With EQ, it is incredible.

Conclusions
Amazing what happens when you follow the science: you get a very nice sounding headphone out of the box despite the budget price. Compromises there to be sure in the form of high distortion that is clearly audible when pushed. And spatial effects that are absent. Can't do much about the distortion other than one notch filter but the rest of the experience is substantially improved with a few filters elevating this headphone to one of my favorites!

I struggled as to what rating to give it given the audible distortion post EQ. Normally products don't get a pass from me on that front but at the end, this is a headphone that attempts to do the right thing and delivers post EQ, an experience that is special. I routinely would notice a note or two in my reference tracks that would make me go, "ooh, that sounded nice." This only only happens with best sounding headphones and speakers.

Net, net, I am going to recommend the Drop + Sennheiser PC38X without EQ. With EQ, it is elevated to one of my favorite budget headphones for for medium to medium high level of listing.

Sennheiser, please bring us more headphones with this kind of tuning!

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As always, questions, comments, recommendations, etc. are welcome.

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Hi,

Here are some thoughts about the EQ.

Notes about the EQ design:
  • The average L/R is used to calculate the score.
  • The resolution is 12 points per octave interpolated from the raw data (provided by @amirm)
  • A Genetic Algorithm is used to optimize the EQ.
  • The EQ Score is designed to MAXIMIZE the Score WHILE fitting the Harman target curve with a fixed complexity.
    This will avoid weird results if one only optimizes for the Score.
    It will probably flatten the Error regression doing so, the tonal balance should be more neutral.
  • The EQs are starting point and may require tuning (certainly at LF).
  • The range above 10kHz is usually not EQed unless smooth enough to do so.
  • I am using PEQ (PK) as from my experience the definition is more consistent across different DSP/platform implementations than shelves.
  • With some HP/amp combo the boosts and preamp gain need to be carefully considered to avoid issues

Excellent L/R match.

I have generated one EQ, the APO config file is attached.
You may want to experiment with the notch @675Hz as proposed by Amirm. The score becomes 95.7.

Score no EQ: 80.8
Score Armirm: 85.3
Score with EQ: 100.8

Code:
DROP + SENNHEISER PC38X APO EQ Flat@HF 96000Hz
June242021-102835

Preamp: -7.3 dB

Filter 1: ON PK Fc 25.45 Hz Gain 7.23 dB Q 0.89
Filter 2: ON PK Fc 195.37 Hz Gain -1.66 dB Q 1.40
Filter 3: ON PK Fc 1446.26 Hz Gain -2.59 dB Q 1.74
Filter 4: ON PK Fc 4207.89 Hz Gain 2.68 dB Q 3.78
Filter 5: ON PK Fc 5159.33 Hz Gain -2.71 dB Q 5.00
Filter 6: ON PK Fc 8167.86 Hz Gain 4.13 dB Q 1.50
Filter 7: ON PK Fc 8519.50 Hz Gain -4.03 dB Q 5.00
Filter 8: ON PK Fc 10437.92 Hz Gain 4.97 dB Q 3.69

DROP + SENNHEISER PC38X Dashboard.png
 

Attachments

  • DROP + SENNHEISER PC38X APO EQ Flat@HF 96000Hz.txt
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I am no gamer, but wouldn't a Gaming headphone with poor spatial qualities out of the box would be a dud? Can you even EQ videogames sound and if so would that help in localizing your opponents? Just curious, it's seams than specifically this would be the very most important thing in gaming no? I have zero experience with that type of use case for headphones so I ask.

EQ options are endless on PC (wide variety of software and/or USB dacs with PEQ). Consoles are much more problematic though. PS4/5 support generic UAC1 DAC's, but don't expose OS level software volume controls requiring DAC manufacturers to either jury-rig their firmwares to get around it, or obscene amounts of amplification to brute force a reasonable volume. The only PEQ UAC1 DAC i'm aware of is the Qudelix-5K, and last I tried, it couldn't drive a usable volume due to said lack of an OS level software volume. They may have released a firmware "hack" to get around this by now, I haven't tried it since last year. Nintendo Switch also support UAC1 DAC and should theoretically support the Qudelix-5K, but I haven't tried it personally. Xbox's blanket don't support generic DAC's at all, so you'd have to rig up some Frankenstein of converters/extractors/ACD's (if it's possible at all).
 
Are there any stand-out reasons to pick the Sennheiser PC38X over the AKG K371 for headphone performance in the $100-150 price range?

This makes me even more curious to see where the Sennheiser HD560S slots in ($200).
 
I would love to see this headphone measured at 60 dBSPL and see if the relative distortion keeps going down.
It has no choice but to keep going down. Transducers are most perfect when they don't move! As to me measuring it, no can do. You need a quite box to get rid of ambient noise. I can build one but they are nearly the size of a coffin and I just don't have room for such a large box.

Distortion grows exponentially so the wind is behind you as play at lower and lower volumes.
 
You may want to experiment with the notch @675Hz as proposed by Amirm. The score becomes 95.7.

Score no EQ: 80.8
Score Armirm: 85.3
Score with EQ: 100.8
So that one notch cut the score by 10 on my EQ?
 
Are there any stand-out reasons to pick the Sennheiser PC38X over the AKG K371 for headphone performance in the $100-150 price range?
They are very different headphones. This one has very large cups compared to the K371. The K371 out of the box has much more bass. But with EQ, you can bring them closer on this front.
 
I have to admit, I am a little confused how a headphone, well anything with this much distortion can warrant a golfing panther, and consider the poor bass response to boot.
Distortion is highly level sensitive. So if you keep the volume down, it performs a lot better on that front. On poor bass, just about every headphone I test needs EQ there so nothing that I can hold against this one post EQ.

But yes, I did say in the review that there are issues with giving this headphone a golfing score. Ultimately I decided it was just.
 
I tried these, but all it did was remind me of this awful cup size paradigm. Why is it that the more space for your ears there is, the more locked away such a purchase is behind a higher price tag? This, then the HD6-- series, then the HD8-- series. You can only get more space, by paying far more...

Hate that.

Otherwise, decent sounding headphone, and the mic quality is pretty good according to playing with people over Discord.
 
I hear this all the time but sadly don't have any experience myself as I don't play games. But I would imagine that any necessary spatial quality is provided by the signal processing in the game and not relying on these subtle effects. I don't even know if these effects are positionally accurate that we talk about here.

What is a Window's game that I can play in demo mode or something to experience such effect?
In all honesty, I wouldn't know, and yes it is provided by signal processing or recording techniques, or both, but, gaming, to me, should be a good measure of spatial quality. I have no expertise on this, I sincerely wonder, but with sound FX the effect is easier to quantify. I don't know, when a gun shot is coming from right behind you, would a headphone good at "spatializing" give you this feeling that it's coming from a speaker behind your back, where others it would be less obvious? I did in the past truly heard this effect, being puzzled when your brain don't register that you are wearing headphones because you hear a sound that's coming from behind. not from the left and right.
 
So that one notch cut the score by 10 on my EQ?

Your EQ without the notch is 88.4 from 85.3.
My EQ without notch is 100.8 and with it 95.7.
 
I hear this all the time but sadly don't have any experience myself as I don't play games. But I would imagine that any necessary spatial quality is provided by the signal processing in the game and not relying on these subtle effects. I don't even know if these effects are positionally accurate that we talk about here.

What is a Window's game that I can play in demo mode or something to experience such effect?
I don't think you need anything special for games. I used a HD480 for ages, which would have been something like €40-50,- at the time (its from the pre-euro era), and that was more than enough to track people in 3D games like the original Counter Strike and Quake 3. This was even before there was super fancy processing in games. Later I used a HD25, also a headphone not known for its spatial qualities, and did the same.
 
Take this with a grain of salt . . . .
Perusing the drop discussion regarding these headphones garners a significant number of quality issues e.g. DOA and component failure. Furthermore it appears (not confirmed) that Sennheiser does not support the product only DROP does. A recipe for disappointment YMMV.
 
Take this with a grain of salt . . . .
Perusing the drop discussion regarding these headphones garners a significant number of quality issues e.g. DOA and component failure. Furthermore it appears (not confirmed) that Sennheiser does not support the product only DROP does. A recipe for disappointment YMMV.
Understood. Does Sennheiser make anything comparable outside of Drop?
 
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